Embolic Stroke due to Pulmonary Vein Thrombosis: A Late Complication of Lung Transplantation.

Pulmonary vein thrombosis (PVT) is a rare condition seen almost exclusively in the first two weeks after lung transplantation or lobectomy. Subsequent embolic phenomena are uncommon. Herein, a 47-year-old male with a history of bilateral lung transplantation presented with transient episodes of acute dysphasia and right arm weakness. Brain MRI revealed cortical infarcts in the territory of the left middle cerebral artery. Transesophageal echocardiogram demonstrated a thrombus in the left lower pulmonary vein. This represents the latest manifestation of a PVT reported in the literature-6 years after redo transplantation and 13 years after the original surgery. Investigation for PVT should be considered in any patient with previous lung transplantation that presents with systemic emboli.

Mechanisms governing the inelastic deformation of cortical bone and application to trabecular bone.

To understand the inelastic response of bone, a three-part investigation has been conducted. In the first, unload/reload tests have been used to characterize the hysteresis and provide insight into the mechanisms causing the strain. The second part devises a model for the stress/strain response, based on understanding developed from the measurements. The model rationalizes the inelastic deformation in tension, as well as the permanent strain and hysteresis. In the third part, a constitutive law representative of the deformation is selected and used to illustrate the coupled buckling and bending of ligaments that arise when trabecular bone is loaded in compression.

A trial of 13-cis-retinoic acid for treatment of squamous cell carcinoma and preneoplastic lesions of the head in cats.

Ten cats with a total of 15 cancerous or precancerous lesions were examined for clinical response to and histopathologic changes after treatment with 13-cis-retinoic acid. Before treatment was started, the lesions were graded according to clinical severity and biopsied for histopathologic examination. Serum samples were prepared for determining vitamin A concentrations. For comparison, serum vitamin A concentrations in 10 clinically healthy cats were determined. 13-cis-Retinoic acid (approx 3.0 mg/kg) was given to affected cats once a day for an average of 68 days. At the completion of the therapeutic trial, additional biopsy tissues were obtained for histopathologic examination, and serum was assayed for 13-cis-retinoic acid. Of the 15 lesions examined, only 1 showed partial clinical and microscopic improvement during the therapy period. The mean serum vitamin A concentration of the affected cats was not statistically different from that of the 10 healthy cats. The results of this trial indicated that 13-cis-retinoic acid used at this dosage, daily frequency, and duration did not have therapeutic efficacy for squamous cell carcinomas or preneoplastic lesions in the cat and that the mean serum vitamin A concentration did not differ between the affected cats and clinically healthy cats.

Intradermal testing of horses with chronic obstructive pulmonary disease and recurrent urticaria.

Six horses with chronic obstructive pulmonary disease (COPD) and 8 horses with recurrent urticaria were skin tested with 67 extracts from 58 allergens, including pollens, epidermals, cultivated farm plants, dusts, molds, and insects. Reactions were evaluated 3 times over a 24-hour period immediately after the injections. Results were compared with those obtained from 11 clinically normal horses. All horses had positive skin test reactions. Significant differences was evident between horses with COPD and clinically normal horses for only 3.0% of the possible extract reactions, and between horses with urticaria and clinically normal horses for only 4.5% of the possible extract reactions. Horses with COPD or urticaria had greater total percentage of allergen extract reactions than did clinically normal horses. Positive reactions were observed at all 3 evaluation periods, and late-onset reactions were not always preceded by positive reaction at earlier periods. All horses with COPD or urticaria had at least 1 skin test reaction that exceeded the mean +/- 2 SD, as calculated for each of the 67 extracts for the group of clinically normal horses.

Allergic inhalant dermatitis attributable to marijuana exposure in a dog.

Exposure to marijuana was believed to be responsible for clinical signs consistent with allergic inhalant dermatitis in a dog. The dog had facial and pedal pruritus associated with bilateral ocular discharge. Clinical signs resolved when the dog was kenneled, but returned when the dog was returned to its home. The results of intradermal skin testing, using a standard tray of 51 inhalant extracts, did not adequately account for the dog's clinical signs. Later, the owners indicated that previous residents of the owners' home had cultivated marijuana intensively inside and outside of the home. Intradermal skin testing with a source of marijuana pollen extract was performed, yielding a positive reaction in the dog and a negative reaction in another dog without clinical or historical evidence of allergic inhalant dermatitis. The affected dog was treated successfully and exclusively by hyposensitization with marijuana pollen extract.

Mosquito bite-caused eosinophilic dermatitis in cats.

Eight cats had lesions on the nasal bridge, ears, and footpads, with histologic and hematologic features of a recently described seasonal form of eosinophilic granuloma complex. Four cats were examined in detail, and it was established that 2 of the 4 reacted to mosquito extract on intradermal skin testing read at 20 minutes. Neither of the 2 cats tested had deposits of immunoglobulins in lesional or perilesional skin. Lesions on all 4 cats resolved when kept at home behind insect screening, but flared up if the screening was removed. Mosquitoes that were observed to be biting and causing lesions were collected and identified. Other species of laboratory-reared mosquitoes were allowed to bite nonlesional skin of 1 affected cat, causing pruritus, erythematous crusting, and ulcerative lesions at the bite site, which was characterized histologically as eosinophilic dermatitis.

Radiocesium in the Savannah River Site environment.

The Savannah River Site has produced plutonium, tritium, and other special nuclear materials for national defense, other government programs, and some civilian purposes. Radiocesium, a waste product, has been released to the environment during the operation of five reactors, two radio-chemical processing facilities, and a high-level waste storage system. During the period 1955-1989, 130 GBq of 137Cs was released to the atmosphere and 2.2 x 10(4) GBq was released to site streams and ponds. Approximately 65% of the latter remained on the site. The maximum individual effective dose equivalent at the site boundary was estimated to be 3.3 microSv from atmospheric releases and 600 microSv from liquid releases. The 80-km population dose was 1.6 person-Sv.

Plutonium in the Savannah River Site environment.

The Savannah River Site has produced plutonium, tritium, and other special nuclear materials for national defense, other government programs, and some civilian purposes. Plutonium has been released to the environment during the operation of five reactors, two radiochemical processing facilities, and other supporting facilities. During the period 1954-1989, 140 GBq of plutonium were released to the atmosphere and 23 GBq were released to site streams and ponds. The maximum individual effective dose equivalent at the site boundary was estimated to be 120 microSv from atmospheric releases and 2.4 microSv from liquid releases. The 80-km population dose was 7.1 person-Sv.

Phosphorylation of histone H3 serine 28 modulates RNA polymerase III-dependent transcription.

Deregulation of RNA polymerase III (Pol III) transcription enhances cellular tRNAs and 5S rRNA production, leading to an increase in translational capacity to promote cell proliferation, transformation and tumor formation. Phosphorylation of histone H3 (H3ph) is induced by tumor promoters (EGF, UV and TPA) and immediate early genes, such as c-myc, c-jun and c-fos. However, it remains to be determined whether H3ph is involved in RNA Pol III transcription. Here, we report that EGF strongly induced H3ph at serine 28 (H3S28ph). EGF significantly increased transcription of RNA Pol III-dependent genes (Pol III genes), tRNA(Leu), tRNA(Tyr), 5S rRNA and 7SL RNA. Inhibition of EGFR, but not PI3K, reduced both H3S28ph and tRNA(Leu) and 5S rRNA transcription. EGF enhanced occupancy of H3S28ph in the promoters of tRNA(Leu) and 5S rRNA. Further analysis indicates that EGF augmented cellular levels of protein and mRNA of TFIIIB subunits, Brf1 and TATA box-binding protein (TBP). Brf1 is a specific transcription factor for RNA Pol III genes. EGF enhanced occupancy of H3S28ph in the Brf1 and TBP promoters. Inhibition of H3S28ph by mutant H3S28A repressed Brf1, TBP and tRNA(Leu) and 5S rRNA expression and decreased occupancy of H3S28ph in their promoters. Reduction of Brf1 significantly decreased tRNA(Leu) and 5S rRNA transcription and repressed EGF-induced anchorage-independent growth. Blocking H3S28ph signaling by using mutant H3S28A reduced EGF-induced cell transformation. Together, these results indicate that EGF activates EGFR signaling to induce H3S28ph, which, in turn, upregulates tRNA(Leu) and 5S rRNA transcription through Brf1 and TBP and promotes cell transformation. The studies demonstrate that epigenetic modification of H3S28ph has a critical role in the activity of Pol III genes.

Simulation of the contractile response of cells on an array of micro-posts.

A bio-chemo-mechanical model has been used to predict the contractile responses of smooth cells on a bed of micro-posts. Predictions obtained for smooth muscle cells reveal that, by converging onto a single set of parameters, the model captures all of the following responses in a self-consistent manner: (i) the scaling of the force exerted by the cells with the number of posts; (ii) actin distributions within the cells, including the rings of actin around the micro-posts; (iii) the curvature of the cell boundaries between the posts; and (iv) the higher post forces towards the cell periphery. Similar correspondences between predictions and measurements have been demonstrated for fibroblasts and mesenchymal stem cells once the maximum stress exerted by the stress fibre bundles has been recalibrated. Consistent with measurements, the model predicts that the forces exerted by the cells will increase with both increasing post stiffness and cell area (or equivalently, post spacing). In conjunction with previous assessments, these findings suggest that this framework represents an important step towards a complete model for the coupled bio-chemo-mechanical responses of cells.

A finite element simulation scheme for biological muscular hydrostats.

An explicit finite element scheme is developed for biological muscular hydrostats such as squid tentacles, octopus arms and elephant trunks. The scheme is implemented by embedding muscle fibers in finite elements. In any given element, the fiber orientation can be assigned arbitrarily and multiple muscle directions can be simulated. The mechanical stress in each muscle fiber is the sum of active and passive parts. The active stress is taken to be a function of activation state, muscle fiber shortening velocity and fiber strain; while the passive stress depends only on the strain. This scheme is tested by simulating extension of a squid tentacle during prey capture; our numerical predictions are in close correspondence with existing experimental results. It is shown that the present finite element scheme can successfully simulate more complex behaviors such as torsion of a squid tentacle and the bending behavior of octopus arms or elephant trunks.